Locally high ohmic contacts in a flip chip device had been identified by backside inspection with LIT as shown in Figure 4903. A mechanical cross section and SEM investigations were able to confirm the root cause which is an additional insulator layer infiltration in the contact area [1].

[1] Schmidt, C., Simon, M., and Altmann, F., "Failure Analysis of Stacked-die Devices by Combining Non-destructive Localization and Target Preparation Methods", Proc 3.5th Intl Symposium for Testing and Failure Analysis (ISTFA), 2009.
[2] Paiboon Tangyunyong and Christian Schmidt, Thermal Defect Detection Techniques, Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.